Ignition mixture



May 14, 1957 J. H. MCLAIN Erm. 2,792,294

IGNITION MIXTURE Original Filed March 7, 1945 INVENTORS JOSEPH H. MCLAIN THEODOR A. RUBLE United States Patent IGNITIGN MIXTURE Joseph H. McLain and Theodore A. Roble, United States Army Original application March 7, 1945, Serial No. 581,538. Divided and this application February 2, 1953, Serial No.339,501

Y 2 Claims. (Cl. 522) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to a new type of fuze and novel compositions used therein, particularly adapted for use with tiring devices of the type generally used with smoke candles, gas grenades, iloatin'g smoke pots andsimilar munitions.

Compositions heretofore used in powder trains had several disadvantages such as instability due to presence of moisture, backiiring due to lack of slag forming material and sensitivity to shock and friction.

Briefly stated, the powder train compositions in one of the embodiments of our invention comprises a primer, first re charge, a delay charge and an ignition charge, all placed into the central bore of the fuze body.

One of the objects of this invention is to provide a rst iire charge, which will be extremely easy to ignite from primer or powder ash and yet not sensitive enough to frictional impact to cause undue hazard in mixing or pressing procedures. This charge must be relatively gasless and have a high burning temperature to act as a relay between a primer and some less sensitive material such as the delay charge.

Another object of this invention is to provide a material which will not deteriorate in storage at high temperatures and humidities and also possess the usual physical requirements as to ease of mixing, ability to ow and to pelleting.

Another object of this invention is to provide a delay charge that would meet the following requirements: It should be gasless, non-hygroscopic and, on burning, should leave a plug-forming residue. It should be insensitive to friction and impact and should possess ease of ignition and propagation with ability to be granulated and pelleted and it should burn with sufficient heat to ignite starter mixtures. The speed of burning should be adjustable by varying proportions of the ingredients.

Another object of this invention is to provide an ignition charge that would be non-hygroscopic, withstand long periods of storage under severe conditions of temperature and humidity, be readily ignitable, yet neither friction or impact sensitive to the degree causing the cornpounding to be hazardous for safe manufacture. It must possess a high burning temperature with a large amount of gas and ash so as to be able to ignite the various materials used with it as starter mixes in munitions of various types.

The fuze of one of the embodiments of our invention is easily manufactured, exhibits better over all functioning both before and after extreme storage conditions and will withstand immersion in water for at least four hours.

Other objects of this invention will be apparent to those skilled in the art upon reading the specification in conjunction with the accompanying drawing in which the single figure is a vertical section of the top portion of a grenade provided with a fuze incorporating the various features of this invention.

Referring to the drawing, a grenade is indicated gem Percent Red lead 53.3- L-2 Silicon 33.7- l-2 Manganese 11.21-1 Celluloid LS1-0.2

It was found in practice that this mixture is extremely easy to ignite from primer or powder ash while at the same time it is not sensitive to frictional impact during mixingand pressing operations. It is gasless and has a high burning temperature so that it acts as a relay between a primer and the delay charge. This material was i found to be stable in storage under severe conditions of temperature and humidity. The specific proportions appear to be critical.

In the preferred embodiment of this invention, the delay charg'e mixture comprises essentially of dry litharge and powdered silicon in the ratio of 4 to 1. Since commercial grades of these materials are used the method of controlling the burning time is accomplished by the addition of varying amounts of inert material such as fullers earth. 0.5% of powdered graphite may be added to the granulated material in order to reduce abrasion of pelleting dies.

As an example of one embodiment of this invention our final improved composition of the charge delay 2 cornprises:

This composition was found to withstand tropical storage for at least 3 months with 96.9% functioning. It is pelleted and loaded into the fuse 9 in the manner described hereinafter.

Burning time of this delay mixture can be varied by changing the proportions of litharge and silicon within the range of from 20% silicon-80% 'litharge to 5% siliconlitharge. This property enables this mixture to be used in other types of munitions.

The delay charge of this type, when burned, leaves a heavy slag to serve as a plug and to prevent backliring in this type of fuze.

The ignition charge 3 forms one of the embodiments of our invention and comprises an intimate mixture of Percent by weight Lead chromate 5925 Silicon 19.6i3 Magnesium 19.6i3 Celluloid 1.8i0.2

Patented May 14, 1957 narily used in fuzes of this type. It gives a large flash andv a large amount of gas.

The size of the ash obtained from this ignition charge can bezvariedby changing the particle size of the lgranulated mixturewithin the range of from through 20 mesh to held on 200 mesh. The larger particle size produces the greater flash.V

In the preferred embodiment of this invention, the loading of the igniter fuze- 9 is effected in the following manner.

The fire charge 4 in a form of a small pellet (0188"1; .008 in diameter weighing 0.300 to 0.400 gram, 0.200"i .010'in height) and a pellet of charge delay 2 (weighing 0.600i-050 grams, 0.300- P.015 in height and 0.008" invdiameter) are pressed. iu place beneath the primer 5 in the fuzevbody under a-dead load pressure of 400- 600 lbs. Anotherv delay charge pellet 2 is added and consolidated in thesame manner, as shown. In order to improve the propagation of burning, aV keyed ram tip is used for the pressing operations.

This is followed by a loose mixture of ignition charge 3 suicient to ll the cavity. Ay closingv disc 6 is then crimped in place and the whole is waterproofed with a solution of 40% wax material in a mixture of benzol and toluene (equal parts by weight) by brush application as is well known in this art.

The top portion of the fuse is protected by an aluminum foil disc 7 stamped into the fuze body and its periphery sealed with a coat of wax and shellac varnish.

The fuze 9 is then assembled, as shown, with striker,

lever, etc., in accordance with the normal procedure well known in this. art.v

The fuze of this invention is economical to manufacture and exhibits better overall functioning both before and after extreme storage conditions. It with withstand immersion in water for at least 4-hours without showing any defects in use. i

In the foregoingY description we described the preferred embodiment of the invention without confining ourselves to the precise details set forth by way of illustration, as it is apparent that many changes and variations may be made therein by those skilled in the art, without departing from thespirit ofthe'invention or exceeding the scopeV of the appended claims.

This applicationy is...a divisionof application Serial No. 581,538, tiled March 7, 1945, now Patent No. 2,643,946.

We claim:

l. An ignition mixture composed of lead chromate 59%, silicon 19.6%, magnesium 19.6%, and Celluloid, 1.8%.

2. Thecompositionof; claim: l inA which the particle size is in the range of from through 20 mesh to held on 200 mesh.

References Cited inthe tile of this patent UNITED STATES PATENTS 1,310,466 Becket July 22, 1919 2,027,825 Jacobs Jan. 14, 1936 2,410,801 Audrieth Nov. 12, 1946 2,457,860 Bennett et al Ian. 4, 1949 

1. AN IGNITION MIXTURE COMPOSED OF LEAD CHROMATE 59%, SILICON 19.6%, MAGNESIUM 19.6%, AND CELLULOID, 1.8%. 